<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>

  <div>heder</div>

  <div id="app"></div>

  <div>footer</div>

  <!-- 添加React的依赖 -->
  <script src="https://unpkg.com/react@16/umd/react.development.js" crossorigin></script>
  <script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js" crossorigin></script>
  <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>

  <!-- 开始开发 -->
  <!-- 注意事项: 使用jsx,并且希望script中的jsx代码被解析,必须在script标签中添加一个属性 -->
  <script type="text/babel">
    // <h2></h2>
    let message = 'hello world'
    ReactDOM.render(<h2>{message}</h2>, document.getElementById('app'))
  </script>
</body>

</html>